Sahih Muslim , Book 33, Hadith 135 (In-Book) ⓘ
It has been narrated on the authority of Ibn 'Umar who said: The Messenger of Allah forbade that one should travel to the land of the enemy taking the Qur'an with him.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، قَالَ نَهَى رَسُولُ اللَّهِ صلى الله عليه وسلم أَنْ يُسَافَرَ بِالْقُرْآنِ إِلَى أَرْضِ الْعَدُوِّ .
also referenced under: Hadith 1869 (Reference) & Book 20, Hadith 4607 (USC-MSA)